Double floor structure of building

Abstract

To provide a double floor structure of a building which can absorb floor impact sound in a wide frequency band.SOLUTION: A double floor structure 1 of a building has a floor slab 2, a floor material 3 opposed to the floor slab 2 at an interval, and a plurality of vibration absorption units 5 which are mounted on a mounting surface 34 opposed to the floor slab 2 of the floor material 3, wherein each of the plurality of vibration absorption units 5 has a plurality of vibration absorbers 52 having different resonance frequencies.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a double floor structure of a building.

Background Art

[0002] In apartment houses, a double floor structure may be adopted for floor finishing. In apartment houses, since countermeasures against floor impact sound generated on the upper floor are required, a double floor structure using an asphalt-based vibration damping sheet or the like may be used, but it is also known to provide a dynamic vibration absorber such as a tuned mass damper (TMD) in the underfloor space. Patent Document 1 describes a sound insulation structure for a floor in which a plurality of sound insulation units are arranged under the floor. Each sound insulation unit has a plurality of dynamic vibration absorbers, and the plurality of dynamic vibration absorbers are fixed to the lower surface of the floor material via a fixing sheet.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Floor impact sound is generated in a frequency band having a certain degree of spread. Therefore, in order to effectively reduce floor impact sound, it is desirable to absorb floor impact sound in a wide frequency band. An object of the present invention is to provide a double floor structure of a building capable of absorbing floor impact sound in a wide frequency band.

Means for Solving the Problems

[0005] The double floor structure of a building according to the present invention includes a floor slab, a floor material facing the floor slab with a space therebetween, and a plurality of vibration absorption units attached to an attachment surface of the floor material facing the floor slab, and each of the plurality of vibration absorption units has a plurality of vibration absorbers having different resonance frequencies.

Effects of the Invention

[0006] According to the present invention, it is possible to provide a double floor structure of a building capable of absorbing floor impact sound in a wide frequency band.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Embodiments for Carrying Out the Invention

[0008] Embodiments of the double floor structure of a building according to the present invention will be described with reference to the drawings. The present invention can be suitably applied to reinforced concrete apartment houses, but can also be applied to wooden apartment houses and detached houses. FIG. 1(a) shows a cross-sectional view of the double floor structure 1, FIG. 1(b) shows an enlarged view of part A of FIG. 1(a), and FIG. 2 shows a plan view of the double floor structure 1 in one room partitioned by the wall 8. In FIG. 2, the illustration of the floor finish material 32 is omitted, and the vibration absorption unit 5 is shown superimposed on the base panel 31 for convenience. In the specification and drawings, the Z direction indicates the vertical direction or the up-and-down direction.

[0009] (Overview of the double floor structure 1) The double - floor structure 1 of the building has a floor slab 2 made of reinforced concrete and a floor material 3 facing the floor slab 2 with a space therebetween. A sub - floor space 6 is formed between the floor slab 2 and the floor material 3. The floor material 3 has a plurality of base panels 31 (particle boards) facing the floor slab 2 and a floor finishing material 32 disposed on the base panels 31. The base panel 31 is a support plate that supports the floor finishing material 32 and is formed of a steel plate or the like. A gap 33 is provided between adjacent base panels 31, and the floor finishing material 32 is formed continuously (without providing a gap). As shown in FIG. 2, the base panel 31 is basically rectangular, but its shape and size may be different from each other or may be a non - rectangular shape. The floor finishing material 32 is a panel that constitutes the floor surface of the living unit and is formed of wood, resin, or the like. As shown in FIG. 1(a), support legs 41 are joined to the bottom surface 34 of the base panel 31. The upper end of the support leg 41 is a support plate 42 that supports the base panel 31. A vibration - absorbing rubber 43 is provided at the bottom of the support leg 41, and the vibration - absorbing rubber 43 is supported by the floor slab 2. That is, each of the plurality of base panels 31 is supported by the floor slab 2 via the support legs 41. As shown in FIG. 2, the support legs 41 are arranged in a grid pattern and at equal intervals at the peripheral edge of the base panel 31. Such a double - floor structure 1 is also called a dry double - floor.

[0010] (Configuration of the vibration - absorbing unit 5) FIG. 3 is an exploded perspective view of one vibration absorption unit 5. The configuration of the vibration absorption unit 5 will be described with reference to FIGS. 1 to 3. At least one vibration absorption unit 5 is attached to the mounting surface 34 facing the floor slab 2 of the floor material 3, specifically, the lower surface 34 of all the base panels 31. That is, the vibration absorption unit 5 is arranged outside the living space. All the vibration absorption units 5 have the same configuration. The vibration absorption unit 5 is closely joined to the base panel 31. A plurality of vibration absorption units 5 can be attached to the lower surface 34 of at least one base panel 31. Each vibration absorption unit 5 has one mounting plate 51 attached to the mounting surface 34 of the base panel 31 and a plurality of vibration absorbers 52 attached to the mounting plate 51. The mounting plate 51 is interposed between the mounting surface 34 and the plurality of vibration absorbers 52. As a result, the vibration absorption unit 5 including the mounting plate 51 is unitized, improving the workability. It is also possible to unitize the base panel 31 and the vibration absorption unit 5, and in this case, the mounting plate 51 may be omitted.

[0011] Each vibration absorber 52 has an elastic body 53 attached to a mounting plate 51 and a weight 54 attached to the lower surface 53B of the elastic body 53. The mounting plate 51, the elastic body 53, and the weight 54 are rectangular or square, but these shapes are not limited and may be any shape such as circular, triangular, trapezoidal, polygonal, etc. The vibration absorber 52 of the present embodiment is a spring-mass type dynamic vibration absorber and is, in principle, a kind of TMD. Since the weight 54 is supported only by the lower surface 53B of the elastic body 53, it can freely vibrate in the vertical direction Z according to the deformation of the elastic body 53. The vibration absorber 52 has a resonance frequency (natural frequency) determined by the elastic coefficient of the elastic body 53 and the mass of the weight 54 with respect to the vibration in the vertical direction Z. When people walk or jump on the floor surface in an apartment building, or when a heavy object is dropped on the floor surface, the vibration in the vertical direction Z is transmitted to the lower floor through the floor material 3 and the floor slab 2. It is known that this vibration is transmitted to the lower floor as floor impact sound mainly in the range of 45 Hz to 90 Hz in an apartment building made of reinforced concrete, and this frequency range is also called the 63 Hz band. The vibration absorber 52 absorbs the floor impact sound at the resonance frequency and the frequencies around it.

[0012] The vibration absorption unit 5 is disposed in the under-floor space 6 between the floor slab 2 and the floor material 3. However, facility piping 7 and the like are also disposed in the under-floor space 6. Therefore, in order to relax the restrictions on the route of the facility piping 7 as much as possible, the thickness h (Z-direction dimension) of the vibration absorption unit 5 is preferably in the range of 10 to 50 mm. The mounting plate 51, the elastic body 53, and the weight 54 are formed in a thin plate-like sheet shape. The upper surface 53A of the elastic body 53 is closely joined to the lower surface 51A (mounting surface 34) of the mounting plate 51, and the upper surface 54A of the weight 54 is closely joined to the lower surface 53B of the elastic body 53. Considering workability, the vibration absorber 52 is preferably joined to the mounting plate 51 with a double-sided tape (not shown). The double-sided tape preferably has a high elastic modulus in the thickness direction, is uniform in thickness, and is thin. In order to prevent peeling of the vibration absorber 52, the four corners of the vibration absorber 52 may be fixed to the mounting plate 51 with screws, tackers, or the like. The vibration absorption unit 5 can also be attached to the base panel 31 by, for example, integral molding, pressure bonding, or the like. Although a downward self-weight acts on the vibration absorption unit 5, with such a configuration, the vibration absorption unit 5 can be firmly fixed to the base panel 31 and can behave integrally with the base panel 31.

[0013] The material of the mounting plate 51 is not limited, but preferably has rigidity, is less likely to change its state due to temperature and humidity changes, and is easily formed into a thin shape. Examples include rubber, steel, concrete, glass, and gypsum board. The material of the elastic body 53 is not limited as long as it has the strength to elastically deform and support the weight 54, but preferably has moisture resistance, water repellency, and durability in consideration of maintenance. Examples include rubber and foamed materials. In order to absorb vibration in a wide frequency range, the damping constant of the elastic body 53 is preferably large. A coil spring can also be used as the elastic body 53. The material of the weight 54 is not limited, but preferably has rigidity, is less likely to change its state due to temperature and humidity changes, and is easily formed into a thin shape. More preferably, it has moisture resistance, water repellency, and durability in consideration of maintenance. Examples of the material of the weight 54 include steel, concrete, glass, resin, and gypsum board.

[0014] (Installation position of the vibration absorption unit 5) Since the base panel 31 is supported by the support legs 41 around it, generally in the first mode, the central part is most displaced in the vertical direction Z (becomes the antinode of vibration). Therefore, considering the vibration absorption performance and constructability, it is preferable to arrange the vibration absorption unit 5 at the central part of the base panel 31 or in its vicinity. However, in the higher-order vibration modes of the base panel 31, the central part of the base panel 31 is not necessarily the most displaced. For this reason, when the vibration absorption unit 5 is locally and concentratedly arranged only in the vicinity of the central part of the base panel 31, although the vibration in the frequency band of the first mode can be absorbed, the vibration of the higher-order mode cannot be effectively absorbed. As a result, the floor impact sound cannot be effectively absorbed.

[0015] For the above reasons, when arranging a plurality of vibration absorption units 5 on each base panel 31, it is preferable that the plurality of vibration absorption units 5 are arranged two-dimensionally and dispersedly on each base panel 31. Specifically, it is preferable to provide a plurality of vibration absorption units 5 at positions that become the antinodes of vibration in the main vibration modes including the first mode. The main vibration modes can be obtained, for example, by finite element analysis or experiments on the base panel 31. However, in the case of a base panel 31 with a small area (for example, the upper right base panel 31 in FIG. 2), it is also possible to arrange only one vibration absorption unit 5 at the center. The total area of the vibration absorption units 5 attached to each rectangular base panel 31 is preferably 10% or more and 70% or less of the area of the largest rectangular region S that does not include the support legs 41 of the base panel 31 in a top view (viewed from above in the Z direction). The total area of the vibration absorption units 5 means the sum of the installation areas of the plurality of vibration absorption units 5 when the plurality of vibration absorption units 5 are attached to one base panel 31.

[0016] (Arrangement of the vibration absorber 52) One vibration absorber unit 5 may include only one vibration absorber 52. However, as described above, in this embodiment, one vibration absorber unit 5 includes a plurality of vibration absorbers 52. In this embodiment, each vibration absorber unit 5 includes nine vibration absorbers 52, but the number of vibration absorbers 52 is not limited. In this embodiment, the plurality of vibration absorbers 52 are arranged in a 3×3 grid pattern, but the arrangement pattern of the vibration absorbers 52 is not limited. For example, they may be arranged in a staggered pattern. Alternatively, the vibration absorbers 52 may be arranged randomly, but in this case, it is also preferable to arrange them as dispersedly as possible. By arranging the plurality of vibration absorbers 52 in a planar manner in this way, each vibration absorber 52 can be miniaturized and lightened. In addition, compared with the case where only one vibration absorber 52 is provided locally, a large vibration absorption effect can be obtained over a wide range of the base panel 31. The vibration mode of the base panel 31 is also affected by construction conditions, the position and weight of floor-mounted objects, and the position of the vibration antinode may vary. By arranging the plurality of vibration absorbers 52 in a planar manner, vibration can be effectively absorbed even in such cases.

[0017] The primary resonance frequencies of the plurality of vibration absorbers 52 may be the same, but the plurality of vibration absorbers 52 preferably include a plurality of vibration absorbers 52 having different primary resonance frequencies. As described above, since the main frequency band of the floor impact sound is 45 Hz to 90 Hz, by providing a plurality of vibration absorbers 52 having different primary resonance frequencies, vibration can be absorbed over a wide frequency band. Since the frequency band width borne by each vibration absorber 52 may be narrow, the attenuation constant of the elastic body 53 may be small. By adopting an elastic body 53 with a small attenuation constant, a large vibration reduction effect can be obtained near the primary resonance frequency. In other words, by arranging a plurality of vibration absorbers 52 having different primary resonance frequencies and reducing the attenuation constant of each elastic body 53, a large vibration reduction effect can be obtained in a wide frequency region. On the other hand, if an elastic body 53 with a large attenuation constant is adopted, the vibration reduction effect near the primary resonance frequency will decrease, but a more uniform vibration reduction effect can be obtained over a wider frequency region. Thus, since a unique effect can be obtained whether the attenuation constant of the elastic body 53 is large or small, the options for the elastic body 53 are expanded.

[0018] FIG. 4 is a schematic plan view showing the arrangement pattern of a plurality of vibration absorbers 52. In the present embodiment, each vibration absorber 52 includes a plurality of first vibration absorbers 52A, a plurality of second vibration absorbers 52B, and a plurality of third vibration absorbers 52C. The plurality of vibration absorbers 52 composed of the first vibration absorber 52A, the second vibration absorber 52B, and the third vibration absorber 52C are arranged in a lattice pattern. The first vibration absorber 52A has a first resonance frequency f1 (50 Hz), the second vibration absorber 52B has a second resonance frequency f2 (63 Hz) different from the first resonance frequency f1, and the third vibration absorber 52C has a third resonance frequency f3 (80 Hz) different from the first and second resonance frequencies f1 and f2. The first to third resonance frequencies f1 to f3 are not limited to this example, but it is preferable to allocate them as evenly as possible to the frequency band of 45 Hz to 90 Hz. For example, when providing the first to nth vibration absorbers each having resonance frequencies f1 to fn, it is preferable to divide the frequency band of 45 Hz to 90 Hz into n equal parts and sequentially assign the resonance frequencies f1 to fn to each region. The number of resonance frequencies different from each other is not limited. The resonance frequency can be easily adjusted by changing the weight of the weight 54, the thickness and material of the elastic body 53, etc.

[0019] In the example shown in FIG. 4(a), each of the plurality of first vibration absorbers 52A, the plurality of second vibration absorbers 52B, and the plurality of third vibration absorbers 52C is dispersedly arranged. That is, each of the plurality of first vibration absorbers 52A, the plurality of second vibration absorbers 52B, and the plurality of third vibration absorbers 52C is not adjacent in the row direction R and the column direction C. As a result, each of the first to third vibration absorbers 52A to 52C can absorb vibrations in a wide range. In the example shown in FIG. 4(b), each of the plurality of first vibration absorbers 52A, the plurality of second vibration absorbers 52B, and the plurality of third vibration absorbers 52C is concentratedly arranged. Such an arrangement pattern is also included in the present embodiment, but the example shown in FIG. 4(a) is more preferable.

[0020] FIG. 5 schematically shows the vibration reduction performance of the vibration absorption unit 5 having the arrangement pattern of the vibration absorbers 52 shown in FIG. 4(a). When the resonance frequencies of all the vibration absorbers 52 are the same, a large vibration reduction effect can be obtained for the vibration frequencies near the resonance frequency, but a sufficient vibration reduction effect cannot be obtained for the vibrations at other frequencies. When the vibration absorption unit 5 has a plurality of resonance frequencies f1 to f3, since the vibration reduction effect can be obtained at each resonance frequency f1 to f3, the floor impact sound can be more effectively reduced as a whole.

[0021] (Effects of the present embodiment) The effects of the present embodiment will be described in comparison with a comparative example. The first comparative example is to thicken the floor slab to increase the rigidity of the floor slab. This method is a general method for reducing floor impact sound, but the increase in the weight of the floor slab causes factors such as an increase in the size and cost of beams and columns. A method of forming voids inside the floor slab and arranging vibration absorbers in the voids is also known, but an increase in the slab thickness may reduce the floor height of the living space. In the present embodiment, it is not necessary to thicken the floor slab 2 itself or change the structure, and the conventional floor slab can be used. Since the vibration absorption unit 5 is small and lightweight, its influence on the design of the floor slab 2 is also minor, if any. Further, since the vibration absorption unit 5 is thin and installed over a wide range, interference with the utility piping 7 is less likely to occur. Since it is not necessary to increase the height of the under-floor space 6, the influence on the floor height is also less likely to occur.

[0022] The second comparative example is a method of inserting a sound insulation sheet between the base panel 31 and the floor finish material 32 to enhance the rigidity of the floor material 3. The thickness of the sound insulation sheet is generally about 6 to 8 mm, and two or more sheets can be stacked and used as required. However, since the sound insulation sheet is mainly made of an asphalt-based material and is provided over the entire floor surface, it is heavy and may affect the building structure. Inserting the sound insulation sheet may also reduce the floor height. There is also a problem of a large amount of carbon dioxide emissions during manufacturing. Since the insertion of the sound insulation sheet needs to be carried out on-site, it also affects the workability. Since the vibration absorption unit 5 of the present embodiment does not need to be provided over the entire floor surface, it can be made lighter than the sound insulation sheet, leading to a reduction in construction costs. Also, since the under-floor space 6 is utilized, it is less likely to affect the floor height. Since an asphalt-based material is not used, environmental considerations are also possible. The amount of on-site work can also be reduced.

[0023] The third comparative example is a method of locally arranging a large TMD in the under-floor space 6. Since the large TMD is heavy, it may be necessary to reinforce the floor material 3. Also, since the large TMD is locally arranged, there may be a need to increase the height of the under-floor space 6 and the degree of freedom in arranging equipment piping 7 etc. may be restricted. In the present embodiment, since the small and thin vibration absorption units 5 are dispersedly arranged, it is less likely to affect the height of the under-floor space 6.

[0024] (Modification example) Although the present invention has been described by way of embodiments, the present invention is not limited to these embodiments. For example, the vibration absorption unit 5 may use a vibration absorber that utilizes resonance. This type of vibration absorber includes a Helmholtz resonance box and a resonance pipe communicating with the Helmholtz resonance box. The resonance frequency depends on the length and cross-sectional area of the resonance pipe, and by adjusting these, the resonance frequency, that is, the resonant vibration frequency, can be adjusted. Since the vibration at the resonance frequency is absorbed by the Helmholtz resonance box, it is possible to use the Helmholtz resonance box as a vibration absorber. A vibration absorption unit provided with a plurality of Helmholtz resonance boxes having different resonance frequencies is applicable to the double-floor structure of the building of the present invention in the same manner as the above-described embodiment.

Explanation of reference numerals

[0025] 1 Double - floor structure of a building 2 Floor slab 3 Floor covering 31 Base panel 34 Mounting surface 41 Support leg 5 Vibration absorption unit 51 Mounting plate 52 Vibration absorber 52A - 52C First - third vibration absorbers 53 Elastic body 54 Weight 6 Space under the floor

Claims

1. A floor slab, a floor material facing the floor slab with a space therebetween, and a plurality of vibration absorption units attached to an attachment surface of the floor material facing the floor slab, wherein each of the plurality of vibration absorption units has a plurality of vibration absorbers with different resonance frequencies, a double floor structure of a building.

2. The plurality of vibration absorbers include a plurality of first vibration absorbers having a first resonance frequency and a plurality of second vibration absorbers having a second resonance frequency different from the first resonance frequency, and each of the plurality of first vibration absorbers and the plurality of second vibration absorbers is dispersedly arranged, the double floor structure of a building according to Claim 1.

3. The plurality of vibration absorbers are arranged two-dimensionally, the double floor structure of a building according to Claim 1.

4. The plurality of vibration absorbers are arranged in a grid pattern, and each of the plurality of first vibration absorbers and the plurality of second vibration absorbers is not adjacent in a row direction and a column direction, the double floor structure of a building according to Claim 2.

5. The floor material has a plurality of base panels and a floor finish material arranged on the plurality of base panels, and at least one of the vibration absorption units is attached to a lower surface of all the base panels, the double floor structure of a building according to any one of Claims 1 to 4.

6. A plurality of the vibration absorption units are attached to the lower surface of at least one of the base panels, the double floor structure of a building according to Claim 5.

7. having a plurality of support legs for supporting the base panels, the base panel is rectangular, In a top view, the total area of the vibration absorption units attached to each rectangular base panel is 10% or more and 70% or less of the area of the largest rectangular region of the base panel excluding the support legs. The double floor structure of a building according to claim 5.

8. Each of the plurality of vibration absorption units has one mounting plate interposed between the lower surface and the plurality of vibration absorbers. The double floor structure of a building according to claim 5.

9. The vibration absorber has an elastic body attached to the mounting plate and a weight attached to the elastic body. The double floor structure of a building according to claim 8.

10. The mounting plate, the elastic body, and the weight are in a thin plate shape. The upper surface of the elastic body is in close contact with the lower surface of the mounting plate, and the upper surface of the weight is in close contact with the lower surface of the elastic body. The double floor structure of a building according to claim 9.

11. The at least one vibration absorption unit is joined to the base panel. The double floor structure of a building according to claim 5.

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